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1.
J Neurophysiol ; 131(4): 577-588, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38380829

RESUMEN

Bistability in spinal motoneurons supports tonic spike activity in the absence of excitatory drive. Earlier work in adult preparations suggested that smaller motoneurons innervating slow antigravity muscle fibers are more likely to generate bistability for postural maintenance. However, whether large motoneurons innervating fast-fatigable muscle fibers display bistability is still controversial. To address this, we examined the relationship between soma size and bistability in lumbar (L4-L5) ventrolateral α-motoneurons of choline acetyltransferase (ChAT)-green fluorescent protein (GFP) and Hb9-GFP mice during the first 4 wk of life. We found that as neuron size increases, the prevalence of bistability rises. Smaller α-motoneurons lack bistability, whereas larger fast α-motoneurons [matrix metalloproteinase-9 (MMP-9)+/Hb9+] with a soma area ≥ 400 µm2 exhibit significantly higher bistability. Ionic currents associated with bistability, including the persistent Nav1.6 current, the thermosensitive Trpm5 Ca2+-activated Na+ current, and the slowly inactivating Kv1.2 current, also scale with cell size. Serotonin evokes full bistability in large motoneurons with partial bistable properties but not in small motoneurons. Our study provides important insights into the neural mechanisms underlying bistability and how motoneuron size correlates with bistability in mice.NEW & NOTEWORTHY Bistability is not a common feature of all mouse spinal motoneurons. It is absent in small, slow motoneurons but present in most large, fast motoneurons. This difference results from differential expression of ionic currents that enable bistability, which are highly expressed in large motoneurons but small or absent in small motoneurons. These results support a possible role for fast motoneurons in maintenance of tonic posture in addition to their known roles in fast movements.


Asunto(s)
Neuronas Motoras , Médula Espinal , Ratones , Animales , Médula Espinal/fisiología , Neuronas Motoras/fisiología , Columna Vertebral , Fibras Musculares Esqueléticas
2.
bioRxiv ; 2023 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-37808773

RESUMEN

Bistability in spinal motoneurons supports tonic spike activity in the absence of excitatory drive. Earlier work in adult preparations suggested that smaller motoneurons innervating slow antigravity muscle fibers are more likely to generate bistability for postural maintenance. However, whether large motoneurons innervating fast-fatigable muscle fibers display bistability related to postural tone is still controversial. To address this, we examined the relationship between soma size and bistability in lumbar ventrolateral α-motoneurons of ChAT-GFP and Hb9-GFP mice across different developmental stages: neonatal (P2-P7), young (P7-P14) and mature (P21-P25). We found that as neuron size increases, the prevalence of bistability rises. Smaller α-motoneurons lack bistability, while larger fast α-motoneurons (MMP-9 + /Hb9 + ) with a soma area ≥ 400µm 2 exhibit significantly higher bistability. Ionic currents associated with bistability, including the persistent Nav1.6 current, thermosensitive Trpm5 Ca 2+ -activated Na + current and the slowly inactivating Kv1.2 current, also scale with cell size. Serotonin evokes full bistability in large motoneurons with partial bistable properties, but not in small motoneurons. Our study provides important insights into the neural mechanisms underlying bistability and how motoneuron size dictates this process. New and Noteworthy: Bistability is not a common feature of all mouse spinal motoneurons. It is absent in small, slow motoneurons but present in most large, fast motoneurons. This difference results from differential expression of ionic currents that enable bistability, which are highly expressed in large motoneurons but small or absent in small motoneurons. These results support a possible role for fast motoneurons in maintenance of tonic posture in addition to their known roles in fast movements.

3.
Glia ; 71(5): 1259-1277, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36645018

RESUMEN

Neuronal rhythmogenesis in the spinal cord is correlated with variations in extracellular K+ levels ([K+ ]e ). Astrocytes play important role in [K+ ]e homeostasis and compute neuronal information. Yet it is unclear how neuronal oscillations are regulated by astrocytic K+ homeostasis. Here we identify the astrocytic inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) as a key molecular player for neuronal rhythmicity in the spinal central pattern generator (CPG). By combining two-photon calcium imaging with electrophysiology, immunohistochemistry and genetic tools, we report that astrocytes display Ca2+ transients before and during oscillations of neighboring neurons. Inhibition of astrocytic Ca2+ transients with BAPTA decreases the barium-sensitive Kir4.1 current responsible of K+ clearance. Finally, we show in mice that Kir4.1 knockdown in astrocytes progressively prevents neuronal oscillations and alters the locomotor pattern resulting in lower motor performances in challenging tasks. These data identify astroglial Kir4.1 channels as key regulators of neuronal rhythmogenesis in the CPG driving locomotion.


Asunto(s)
Astrocitos , Neuronas , Ratones , Animales , Astrocitos/fisiología , Médula Espinal , Inmunohistoquímica , Periodicidad
4.
J Sports Sci ; 40(17): 1981-1990, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36251983

RESUMEN

Citrulline malate (CM) has been shown to improve muscle performance in healthy participants during a single exercise session. Yet, within the framework of exercises repeated at close time interval, the consequences of CM ingestion on mechanical performance are controversial and the bioenergetics side remains undocumented. The aim of this double-blind placebo-controlled study was to evaluate in vivo the effect of short-term (7 doses in 48 h) oral administration of CM upon gastrocnemius muscle function and bioenergetics using non-invasive multimodal NMR techniques in healthy rats. The experimental protocol consisted of two 6-min bouts of fatiguing exercise spaced by an 8-min recovery period. CM treatment did not affect the basal bioenergetics status and increased the half-fatigue time during the first exercise bout. With exercise repetition, it prevented PCr cost alteration and decreased both the glycolytic ATP production and the contractile ATP cost in working muscle, but these changes were not associated to any improvement in mechanical performance. In addition, CM did not influence the replenishment of high-energy phosphorylated compounds during the post-exercise recovery periods. Therefore, short-term CM administration enhances muscle bioenergetics throughout fatiguing bouts of exercise repeated at close time interval but this enhancement does not benefit to mechanical performance.


Asunto(s)
Citrulina , Fatiga Muscular , Animales , Ratas , Adenosina Trifosfato/metabolismo , Adenosina Trifosfato/farmacología , Citrulina/farmacología , Citrulina/metabolismo , Suplementos Dietéticos , Metabolismo Energético , Fatiga , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología
5.
Nat Commun ; 12(1): 6815, 2021 11 24.
Artículo en Inglés | MEDLINE | ID: mdl-34819493

RESUMEN

Bistable motoneurons of the spinal cord exhibit warmth-activated plateau potential driven by Na+ and triggered by a brief excitation. The thermoregulating molecular mechanisms of bistability and their role in motor functions remain unknown. Here, we identify thermosensitive Na+-permeable Trpm5 channels as the main molecular players for bistability in mouse motoneurons. Pharmacological, genetic or computational inhibition of Trpm5 occlude bistable-related properties (slow afterdepolarization, windup, plateau potentials) and reduce spinal locomotor outputs while central pattern generators for locomotion operate normally. At cellular level, Trpm5 is activated by a ryanodine-mediated Ca2+ release and turned off by Ca2+ reuptake through the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump. Mice in which Trpm5 is genetically silenced in most lumbar motoneurons develop hindlimb paresis and show difficulties in executing high-demanding locomotor tasks. Overall, by encoding bistability in motoneurons, Trpm5 appears indispensable for producing a postural tone in hindlimbs and amplifying the locomotor output.


Asunto(s)
Locomoción/fisiología , Neuronas Motoras/metabolismo , Paresia/fisiopatología , Médula Espinal/fisiología , Canales Catiónicos TRPM/metabolismo , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Animales Recién Nacidos , Simulación por Computador , Modelos Animales de Enfermedad , Femenino , Silenciador del Gen , Células HEK293 , Miembro Posterior/fisiología , Humanos , Locomoción/efectos de los fármacos , Masculino , Ratones , Neuronas Motoras/efectos de los fármacos , Paresia/genética , Técnicas de Placa-Clamp , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Rianodina/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/antagonistas & inhibidores , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Médula Espinal/citología , Canales Catiónicos TRPM/antagonistas & inhibidores , Canales Catiónicos TRPM/genética
6.
Physiol Rep ; 7(10): e14055, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-31124296

RESUMEN

Tumor protein 53-induced nuclear protein 1 (TP53INP1) deficiency leads to oxidative stress-associated obesity and insulin resistance. Although skeletal muscle has a predominant role in the development of metabolic syndrome, the bioenergetics and functional consequences of TP53INP1 deficiency upon this tissue remain undocumented. To clarify this issue, gastrocnemius muscle mechanical performance, energy metabolism, and anatomy were investigated in TP53INP1-deficient and wild-type mice using a multidisciplinary approach implementing noninvasive multimodal-NMR techniques. TP53INP1 deficiency increased body adiposity but did not affect cytosolic oxidative stress, lipid content, and mitochondrial pool and capacity in myocyte. During a fatiguing bout of exercise, the in vivo oxidative ATP synthesis capacity was dramatically reduced in TP53INP1-deficient mice despite ADP level (the main in vivo stimulator of mitochondrial respiration) did not differ between both genotypes. Moreover, TP53INP1 deficiency did not alter fatigue resistance but paradoxically increased the contractile force, whereas there were no differences for muscle fiber-type distribution and calcium homeostasis between both genotypes. In addition, muscle proton efflux was decreased in TP53INP1-deficient mice, thereby indicating a reduced blood supply. In conclusion, TP53INP1 plays a role in muscle function and bioenergetics through oxidative capacity impairment possibly as the consequence of abnormal mitochondrial respiration regulation and/or defective blood supply.


Asunto(s)
Metabolismo Energético , Mitocondrias Musculares/metabolismo , Contracción Muscular , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/metabolismo , Proteínas Nucleares/deficiencia , Estrés Oxidativo , Adenosina Trifosfato/metabolismo , Adiposidad , Animales , Genotipo , Imagen por Resonancia Magnética , Espectroscopía de Resonancia Magnética , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Fatiga Muscular , Fuerza Muscular , Músculo Esquelético/diagnóstico por imagen , Proteínas Nucleares/genética , Oxidación-Reducción , Fenotipo , Flujo Sanguíneo Regional
7.
Muscle Nerve ; 58(6): 834-842, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-30025155

RESUMEN

INTRODUCTION: Postnatal activin/myostatin type IIB receptor (ActRIIB) blockade increases skeletal muscle mass and strength but also increases muscle fatigability and impairs oxidative metabolism. The objective of this study was to determine in vivo whether this increased fatigability is due to energy supply limitation. METHODS: The impact of 8-week ActRIIB blockade with soluble receptor (sActRIIB-Fc) on muscle function and adenosine triphosphate (ATP) fluxes was investigated noninvasively by using multimodal magnetic resonance and indirect calorimetry measurements in wild-type mice. RESULTS: Activin/myostatin type IIB receptor blockade reduced (-41%) the muscle apparent mitochondrial capacity and increased (+11%) the basal body energy expenditure. During a fatiguing exercise, ActRIIB blockade decreased both oxidative ATP production rate (-32%) and fatigue resistance (-36%), but these changes affected neither the total ATP production rate nor the contractile ATP cost. DISCUSSION: These findings demonstrate that the increased fatigability after ActRIIB blockade is not due to limitation in energy supply and/or disturbance in contractile ATP cost. Muscle Nerve 58:834-842, 2018.


Asunto(s)
Receptores de Activinas Tipo II/metabolismo , Adenosina Trifosfato/metabolismo , Músculo Esquelético/fisiología , Receptores de Activinas Tipo II/antagonistas & inhibidores , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Animales , Peso Corporal/efectos de los fármacos , Calorimetría , Creatina/metabolismo , Metabolismo Energético , Femenino , Espectroscopía de Resonancia Magnética , Ratones , Ratones Endogámicos C57BL , Contracción Muscular/efectos de los fármacos , Contracción Muscular/fisiología , Músculo Esquelético/efectos de los fármacos , Proteínas Recombinantes de Fusión/farmacología , Estadísticas no Paramétricas
8.
Biochimie ; 148: 36-45, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29499298

RESUMEN

The functional and bioenergetics impact of regular physical activity upon type-2 diabetic skeletal muscle independently of confounding factors of overweight remains undocumented. Here, gastrocnemius muscle energy fluxes, mitochondrial capacity and mechanical performance were assessed noninvasively and longitudinally in non-obese diabetic Goto-Kakizaki rats using magnetic resonance (MR) imaging and dynamic 31-phosphorus MR spectroscopy (31P-MRS) throughout a 6-min fatiguing bout of exercise performed before, in the middle (4-week) and at the end of an 8-week training protocol consisting in 60-min daily run on a treadmill. The training protocol reduced plasmatic insulin level (-61%) whereas blood glucose and non-esterified fatty acids levels remained unaffected, thereby indicating an improvement of insulin sensitivity. It also increased muscle mitochondrial citrate synthase activity (+45%) but this increase did not enhance oxidative ATP synthesis capacity in working muscle in vivo while glycolytic ATP production was increased (+33%). On the other hand, the training protocol impaired maximal force-generating capacity (-9%), total amount of force produced (-12%) and increased ATP cost of contraction (+32%) during the fatiguing exercise. Importantly, these deleterious effects were transiently worsened in the middle of the 8-week period, in association with reduced oxidative capacity and increased basal [Pi]/[PCr] ratio (an in vivo biomarker of muscle damage). These data demonstrate that the beneficial effect of regular training on insulin sensitivity in non-obese diabetic rat occurs separately from any improvement in muscle mitochondrial function and might be linked to an increased capacity for metabolizing glucose through anaerobic process in exercising muscle.


Asunto(s)
Diabetes Mellitus Tipo 2/metabolismo , Metabolismo Energético , Tolerancia al Ejercicio , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal , Adenosina Trifosfato/metabolismo , Animales , Fenómenos Biomecánicos , Diabetes Mellitus Tipo 2/fisiopatología , Resistencia a la Insulina , Masculino , Contracción Muscular , Músculo Esquelético/fisiopatología , Ratas
9.
Malar J ; 16(1): 5, 2017 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-28049524

RESUMEN

BACKGROUND: Malaria is still a major public health issue worldwide, and one of the best approaches to fight the disease remains vector control. The current methods for mosquito identification include morphological methods that are generally time-consuming and require expertise, and molecular methods that require laboratory facilities with relatively expensive running costs. Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) technology, routinely used for bacterial identification, has recently emerged in the field of entomology. The aim of the present study was to assess whether MALDI-TOF MS could successfully distinguish Anopheles stephensi mosquitoes according to their Plasmodium infection status. METHODS: C57BL/6 mice experimentally infected with Plasmodium berghei were exposed to An. stephensi bites. For the determination of An. stephensi infection status, mosquito cephalothoraxes were dissected and submitted to mass spectrometry analyses and DNA amplification for molecular analysis. Spectra were grouped according to mosquitoes' infection status and spectra quality was validated based on intensity and reproducibility within each group. The in-lab MALDI-TOF MS arthropod reference spectra database, upgraded with representative spectra from both groups (infected/non-infected), was subsequently queried blindly with cephalothorax spectra from specimens of both groups. RESULTS: The MALDI TOF MS profiles generated from protein extracts prepared from the cephalothorax of An. stephensi allowed distinction between infected and uninfected mosquitoes. Correct classification was obtained in blind test analysis for (79/80) 98.75% of all mosquitoes tested. Only one of 80 specimens, an infected mosquito, was misclassified in the blind test analysis. CONCLUSIONS: Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry appears to be a promising, rapid and reliable tool for the epidemiological surveillance of Anopheles vectors, including their identification and their infection status.


Asunto(s)
Anopheles/parasitología , Productos Biológicos/análisis , Entomología/métodos , Plasmodium berghei/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Animales , Anopheles/crecimiento & desarrollo , Femenino , Ratones Endogámicos C57BL
10.
FASEB J ; 30(10): 3551-3562, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27416839

RESUMEN

Postnatal blockade of the activin type IIB receptor (ActRIIB) represents a promising therapeutic strategy for counteracting dystrophic muscle wasting. However, its impact on muscle function and bioenergetics remains poorly documented in physiologic conditions. We have investigated totally noninvasively the effect of 8-wk administration of either soluble ActRIIB signaling inhibitor (sActRIIB-Fc) or vehicle PBS (control) on gastrocnemius muscle force-generating capacity, energy metabolism, and anatomy in dystrophic mdx mice using magnetic resonance (MR) imaging and dynamic [31P]-MR spectroscopy ([31P]-MRS) in vivo ActRIIB inhibition increased muscle volume (+33%) without changing fiber-type distribution, and increased basal animal oxygen consumption (+22%) and energy expenditure (+23%). During an in vivo standardized fatiguing exercise, maximum and total absolute contractile forces were larger (+40 and 24%, respectively) in sActRIIB-Fc treated animals, whereas specific force-generating capacity and fatigue resistance remained unaffected. Furthermore, sActRIIB-Fc administration did not alter metabolic fluxes, ATP homeostasis, or contractile efficiency during the fatiguing bout of exercise, although it dramatically reduced the intrinsic mitochondrial capacity for producing ATP. Overall, sActRIIB-Fc treatment increased muscle mass and strength without altering the fundamental weakness characteristic of dystrophic mdx muscle. These data support the clinical interest of ActRIIB blockade for reversing dystrophic muscle wasting.-Béchir, N., Pecchi, E., Vilmen, C., Le Fur, Y., Amthor, H., Bernard, M., Bendahan, D., Giannesini, B. ActRIIB blockade increases force-generating capacity and preserves energy supply in exercising mdx mouse muscle in vivo.


Asunto(s)
Receptores de Activinas Tipo II/antagonistas & inhibidores , Metabolismo Energético/fisiología , Contracción Muscular/fisiología , Músculo Esquelético/metabolismo , Distrofia Muscular Animal/patología , Animales , Peso Corporal/fisiología , Espectroscopía de Resonancia Magnética/métodos , Ratones , Ratones Endogámicos mdx , Modelos Animales , Condicionamiento Físico Animal/métodos
11.
Am J Physiol Endocrinol Metab ; 310(7): E539-49, 2016 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-26837807

RESUMEN

Because it leads to a rapid and massive muscle hypertrophy, postnatal blockade of the activin type IIB receptor (ActRIIB) is a promising therapeutic strategy for counteracting muscle wasting. However, the functional consequences remain very poorly documented in vivo. Here, we have investigated the impact of 8-wk ActRIIB blockade with soluble receptor (sActRIIB-Fc) on gastrocnemius muscle anatomy, energy metabolism, and force-generating capacity in wild-type mice, using totally noninvasive magnetic resonance imaging (MRI) and dynamic(31)P-MRS. Compared with vehicle (PBS) control, sActRIIB-Fc treatment resulted in a dramatic increase in body weight (+29%) and muscle volume (+58%) calculated from hindlimb MR imaging, but did not alter fiber type distribution determined via myosin heavy chain isoform analysis. In resting muscle, sActRIIB-Fc treatment induced acidosis and PCr depletion, thereby suggesting reduced tissue oxygenation. During an in vivo fatiguing exercise (6-min repeated maximal isometric contraction electrically induced at 1.7 Hz), maximal and total absolute forces were larger in sActRIIB-Fc treated animals (+26 and +12%, respectively), whereas specific force and fatigue resistance were lower (-30 and -37%, respectively). Treatment with sActRIIB-Fc further decreased the maximal rate of oxidative ATP synthesis (-42%) and the oxidative capacity (-34%), but did not alter the bioenergetics status in contracting muscle. Our findings demonstrate in vivo that sActRIIB-Fc treatment increases absolute force-generating capacity and reduces mitochondrial function in glycolytic gastrocnemius muscle, but this reduction does not compromise energy status during sustained activity. Overall, these data support the clinical interest of postnatal ActRIIB blockade.


Asunto(s)
Receptores de Activinas Tipo II/antagonistas & inhibidores , Peso Corporal/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Mitocondrias Musculares/efectos de los fármacos , Fibras Musculares Esqueléticas/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Condicionamiento Físico Animal , Proteínas Recombinantes de Fusión/farmacología , Animales , Glucólisis , Imagen por Resonancia Magnética , Espectroscopía de Resonancia Magnética , Ratones , Mitocondrias Musculares/metabolismo , Contracción Muscular/efectos de los fármacos , Fuerza Muscular/efectos de los fármacos , Músculo Esquelético/anatomía & histología , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiopatología , Cadenas Pesadas de Miosina/efectos de los fármacos , Cadenas Pesadas de Miosina/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Isótopos de Fósforo
12.
PLoS One ; 10(6): e0128016, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26030806

RESUMEN

Chronic administration of capsiate is known to accelerate whole-body basal energy metabolism, but the consequences in exercising skeletal muscle remain very poorly documented. In order to clarify this issue, the effect of 2-week daily administration of either vehicle (control) or purified capsiate (at 10- or 100-mg/kg body weight) on skeletal muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in mice. Mechanical performance and energy metabolism were assessed strictly non-invasively in contracting gastrocnemius muscle using magnetic resonance (MR) imaging and 31-phosphorus MR spectroscopy (31P-MRS). Regardless of the dose, capsiate treatments markedly disturbed basal bioenergetics in vivo including intracellular pH alkalosis and decreased phosphocreatine content. Besides, capsiate administration did affect neither mitochondrial uncoupling protein-3 gene expression nor both basal and maximal oxygen consumption in isolated saponin-permeabilized fibers, but decreased by about twofold the Km of mitochondrial respiration for ADP. During a standardized in vivo fatiguing protocol (6-min of repeated maximal isometric contractions electrically induced at a frequency of 1.7 Hz), both capsiate treatments reduced oxidative cost of contraction by 30-40%, whereas force-generating capacity and fatigability were not changed. Moreover, the rate of phosphocreatine resynthesis during the post-electrostimulation recovery period remained unaffected by capsiate. Both capsiate treatments further promoted muscle mass gain, and the higher dose also reduced body weight gain and abdominal fat content. These findings demonstrate that, in addition to its anti-obesity effect, capsiate supplementation improves oxidative metabolism in exercising muscle, which strengthen this compound as a natural compound for improving health.


Asunto(s)
Capsaicina/análogos & derivados , Suplementos Dietéticos , Contracción Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/fisiología , Condicionamiento Físico Animal/fisiología , Grasa Abdominal/efectos de los fármacos , Animales , Fenómenos Biomecánicos/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Capsaicina/administración & dosificación , Capsaicina/farmacología , Respiración de la Célula/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Canales Iónicos/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Proteínas Mitocondriales/genética , Músculo Esquelético/anatomía & histología , Músculo Esquelético/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Oxidación-Reducción/efectos de los fármacos , Permeabilidad/efectos de los fármacos , Proteína Desacopladora 3
13.
PLoS One ; 10(6): e0129579, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26057538

RESUMEN

Insulin resistance, altered lipid metabolism and mitochondrial dysfunction in skeletal muscle would play a major role in type 2 diabetes mellitus (T2DM) development, but the causal relationships between these events remain conflicting. To clarify this issue, gastrocnemius muscle function and energetics were investigated throughout a multidisciplinary approach combining in vivo and in vitro measurements in Goto-Kakizaki (GK) rats, a non-obese T2DM model developing peripheral insulin resistant without abnormal level of plasma non-esterified fatty acids (NEFA). Wistar rats were used as controls. Mechanical performance and energy metabolism were assessed strictly non-invasively using magnetic resonance (MR) imaging and 31-phosphorus MR spectroscopy (31P-MRS). Compared with control group, plasma insulin and glucose were respectively lower and higher in GK rats, but plasma NEFA level was normal. In resting GK muscle, phosphocreatine content was reduced whereas glucose content and intracellular pH were both higher. However, there were not differences between both groups for basal oxidative ATP synthesis rate, citrate synthase activity, and intramyocellular contents for lipids, glycogen, ATP and ADP (an important in vivo mitochondrial regulator). During a standardized fatiguing protocol (6 min of maximal repeated isometric contractions electrically induced at a frequency of 1.7 Hz), mechanical performance and glycolytic ATP production rate were reduced in diabetic animals whereas oxidative ATP production rate, maximal mitochondrial capacity and ATP cost of contraction were not changed. These findings provide in vivo evidence that insulin resistance is not caused by an impairment of mitochondrial function in this diabetic model.


Asunto(s)
Diabetes Mellitus Experimental/patología , Diabetes Mellitus Experimental/fisiopatología , Resistencia a la Insulina , Mitocondrias/metabolismo , Contracción Muscular , Músculo Esquelético/fisiopatología , Adenosina Trifosfato/metabolismo , Animales , Diabetes Mellitus Experimental/metabolismo , Estimulación Eléctrica , Metabolismo Energético , Concentración de Iones de Hidrógeno , Imagen por Resonancia Magnética , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Fosfocreatina/metabolismo , Ratas , Ratas Wistar , Factores de Tiempo
14.
PLoS One ; 9(9): e109066, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25268244

RESUMEN

Nemaline myopathy is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. The first disease causing mutation (Met9Arg) was identified in the gene encoding α-tropomyosin slow gene (TPM3). Considering the conflicting findings of the previous studies on the transgenic (Tg) mice carrying the TPM3Met9Arg mutation, we investigated carefully the effect of the Met9Arg mutation in 8-9 month-old Tg(TPM3)Met9Arg mice on muscle function using a multiscale methodological approach including skinned muscle fibers analysis and in vivo investigations by magnetic resonance imaging and 31-phosphorus magnetic resonance spectroscopy. While in vitro maximal force production was reduced in Tg(TPM3)Met9Arg mice as compared to controls, in vivo measurements revealed an improved mechanical performance in the transgenic mice as compared to the former. The reduced in vitro muscle force might be related to alterations occurring at the cross-bridges level with muscle-specific underlying mechanisms. In vivo muscle improvement was not associated with any changes in either muscle volume or energy metabolism. Our findings indicate that TPM3(Met9Arg) mutation leads to a mild muscle weakness in vitro related to an alteration at the cross-bridges level and a paradoxical gain of muscle function in vivo. These results clearly point out that in vitro alterations are muscle-dependent and do not necessarily translate into similar changes in vivo.


Asunto(s)
Debilidad Muscular/fisiopatología , Músculo Esquelético/fisiopatología , Miopatías Nemalínicas/fisiopatología , Tropomiosina/genética , Adenosina Trifosfato/metabolismo , Animales , Fenómenos Biomecánicos , Modelos Animales de Enfermedad , Metabolismo Energético , Imagen por Resonancia Magnética , Ratones , Ratones Transgénicos , Debilidad Muscular/metabolismo , Debilidad Muscular/patología , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Mutación , Miopatías Nemalínicas/genética , Miopatías Nemalínicas/metabolismo , Miopatías Nemalínicas/patología , Troponina I/metabolismo
15.
Am J Physiol Endocrinol Metab ; 306(10): E1110-9, 2014 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-24644244

RESUMEN

Capsiate is known to increase whole body oxygen consumption possibly via the activation of uncoupling processes, but its effect at the skeletal muscle level remains poorly documented and conflicting. To clarify this issue, gastrocnemius muscle function and energetics were investigated in mice 2 h after a single intake of either vehicle (control) or purified capsiate (at 10 or 100 mg/kg body wt) through a multidisciplinary approach combining in vivo and in vitro measurements. Mechanical performance and energy pathway fluxes were assessed strictly noninvasively during a standardized electrostimulation-induced exercise, using an original device implementing 31-phosphorus magnetic resonance spectroscopy, and mitochondrial respiration was evaluated in isolated saponin-permeabilized fibers. Compared with control, both capsiate doses produced quantitatively similar effects at the energy metabolism level, including an about twofold decrease of the mitochondrial respiration sensitivity for ADP. Interestingly, they did not alter either oxidative phosphorylation or uncoupling protein 3 gene expression at rest. During 6 min of maximal repeated isometric contractions, both doses reduced the amount of ATP produced from glycolysis and oxidative phosphorylation but increased the relative contribution of oxidative phosphorylation to total energy turnover (+28 and +21% in the 10- and 100-mg groups, respectively). ATP cost of twitch force generation was further reduced in the 10- (-35%) and 100-mg (-45%) groups. Besides, the highest capsiate dose also increased the twitch force-generating capacity. These data present capsiate as a helpful candidate to enhance both muscle performance and oxidative phosphorylation during exercise, which could constitute a nutritional approach for improving health and preventing obesity and associated metabolic disorders.


Asunto(s)
Fenómenos Biomecánicos/efectos de los fármacos , Capsaicina/análogos & derivados , Metabolismo Energético/efectos de los fármacos , Contracción Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Animales , Capsaicina/administración & dosificación , Células Cultivadas , Estimulación Eléctrica , Masculino , Ratones , Ratones Endogámicos C57BL , Contracción Muscular/fisiología , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal/fisiología
16.
Arthritis Res Ther ; 16(1): R16, 2014 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-24438745

RESUMEN

INTRODUCTION: Nerve growth factor (NGF) level is increased in osteoarthritis (OA) joints and is involved in pain associated with OA. Stimuli responsible for NGF stimulation in chondrocytes are unknown. We investigated whether mechanical stress and proinflammatory cytokines may influence NGF synthesis by chondrocytes. METHODS: Primary cultures of human OA chondrocytes, newborn mouse articular chondrocytes or cartilage explants were stimulated by increasing amounts of IL-1ß, prostaglandin E2 (PGE2), visfatin/nicotinamide phosphoribosyltransferase (NAMPT) or by cyclic mechanical compression (0.5 Hz, 1 MPa). Before stimulation, chondrocytes were pretreated with indomethacin, Apo866, a specific inhibitor of NAMPT enzymatic activity, or transfected by siRNA targeting visfatin/NAMPT. mRNA NGF levels were assessed by real-time quantitative PCR and NGF released into media was determined by ELISA. RESULTS: Unstimulated human and mouse articular chondrocytes expressed low levels of NGF (19.2 ± 8.7 pg/mL, 13.5 ± 1.0 pg/mL and 4.4 ± 0.8 pg/mL/mg tissue for human and mouse articular chondrocytes and costal explants, respectively). Mechanical stress induced NGF release in conditioned media. When stimulated by IL-1ß or visfatin/NAMPT, a proinflammatory adipokine produced by chondocytes in response to IL-1ß, a dose-dependent increase in NGF mRNA expression and NGF release in both human and mouse chondrocyte conditioned media was observed. Visfatin/NAMPT is also an intracellular enzyme acting as the rate-limiting enzyme of the generation of NAD. The expression of NGF induced by visfatin/NAMPT was inhibited by Apo866, whereas IL-1ß-mediated NGF expression was not modified by siRNA targeting visfatin/NAMPT. Interestingly, PGE2, which is produced by chondrocytes in response to IL-1ß and visfatin/NAMPT, did not stimulate NGF production. Consistently, indomethacin, a cyclooxygenase inhibitor, did not counteract IL-1ß-induced NGF production. CONCLUSIONS: These results show that mechanical stress, IL-1ß and extracellular visfatin/NAMPT, all stimulated the expression and release of NGF by chondrocytes and thus suggest that the overexpression of visfatin/NAMPT and IL-1ß in the OA joint and the increased mechanical loading of cartilage may mediate OA pain via the stimulation of NGF expression and release by chondrocytes.


Asunto(s)
Condrocitos/metabolismo , Inflamación/metabolismo , Factor de Crecimiento Nervioso/biosíntesis , Osteoartritis/metabolismo , Animales , Cartílago Articular/metabolismo , Células Cultivadas , Citocinas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Humanos , Ratones , Osteoartritis/complicaciones , Dolor/etiología , Dolor/metabolismo , Estimulación Física , ARN Interferente Pequeño , Reacción en Cadena en Tiempo Real de la Polimerasa , Transfección
17.
PLoS One ; 8(4): e61517, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23613869

RESUMEN

Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and (31)Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1-150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (-40%) and specific (-25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level.


Asunto(s)
Actinas/metabolismo , Imagen por Resonancia Magnética/métodos , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Miopatías Nemalínicas/metabolismo , Miopatías Nemalínicas/patología , Actinas/genética , Animales , Metabolismo Energético/genética , Metabolismo Energético/fisiología , Femenino , Ratones , Ratones Mutantes , Miopatías Nemalínicas/genética
18.
J Biol Chem ; 287(18): 15100-8, 2012 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-22399297

RESUMEN

Visfatin (also termed pre-B-cell colony-enhancing factor (PBEF) or nicotinamide phosphoribosyltransferase (Nampt)) is a pleiotropic mediator acting on many inflammatory processes including osteoarthritis. Visfatin exhibits both an intracellular enzymatic activity (nicotinamide phosphoribosyltransferase, Nampt) leading to NAD synthesis and a cytokine function via the binding to its hypothetical receptor. We recently reported the role of visfatin in prostaglandin E(2) (PGE(2)) synthesis in chondrocytes. Here, our aim was to characterize the signaling pathways involved in this response in exploring both the insulin receptor (IR) signaling pathway and Nampt activity. IR was expressed in human and murine chondrocytes, and visfatin triggered Akt phosphorylation in murine chondrocytes. Blocking IR expression with siRNA or activity using the hydroxy-2-naphthalenyl methyl phosphonic acid tris acetoxymethyl ester (HNMPA-(AM)(3)) inhibitor diminished visfatin-induced PGE(2) release in chondrocytes. Moreover, visfatin-induced IGF-1R(-/-) chondrocytes released higher concentration of PGE(2) than IGF-1R(+/+) cells, a finding confirmed with an antibody that blocked IGF-1R. Using RT-PCR, we found that visfatin did not regulate IR expression and that an increased insulin release was also unlikely to be involved because insulin was unable to increase PGE(2) release. Inhibition of Nampt activity using the APO866 inhibitor gradually decreased PGE(2) release, whereas the addition of exogenous nicotinamide increased it. We conclude that the proinflammatory actions of visfatin in chondrocytes involve regulation of IR signaling pathways, possibly through the control of Nampt enzymatic activity.


Asunto(s)
Condrocitos/metabolismo , Citocinas/metabolismo , Insulina/metabolismo , Nicotinamida Fosforribosiltransferasa/metabolismo , Transducción de Señal , Acrilamidas/farmacología , Animales , Células Cultivadas , Condrocitos/patología , Citocinas/genética , Dinoprostona/biosíntesis , Dinoprostona/genética , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Humanos , Inflamación/genética , Inflamación/metabolismo , Inflamación/patología , Insulina/genética , Ratones , Ratones Noqueados , Naftalenos/farmacología , Nicotinamida Fosforribosiltransferasa/genética , Organofosfonatos/farmacología , Piperidinas/farmacología , Receptor IGF Tipo 1/biosíntesis , Receptor IGF Tipo 1/genética , Receptor de Insulina/biosíntesis , Receptor de Insulina/genética
19.
J Neuroinflammation ; 6: 27, 2009 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-19778412

RESUMEN

Recently, a novel factor with anorexigenic properties was identified and called nesfatin-1. This protein (82 aac) is not only expressed in peripheral organs but it is also found in neurons located in specific structures including the hypothalamus and the brainstem, two sites strongly involved in food intake regulation. Here, we studied whether some of the neurons that become activated following an injection of an anorectic dose of lipopolysaccharides (LPS) exhibit a nesfatin-1 phenotype. To this end, we used double immunohistochemistry to target the expression of the immediate-early gene c-fos and of nesfatin-1 on coronal frozen sections of the rat brain. The number of c-Fos+/nesfatin-1+ neurons was evaluated in the immunosensitive structures reported to contain nesfatin-1 neurons; i.e. paraventricular hypothalamic nucleus (PVN), supraoptic nucleus (SON), arcuate nucleus (ARC) and nucleus of the solitary tract (NTS). LPS strongly increased the number of c-Fos+/nesfatin-1+ neurons in the PVN, SON and NTS, and to a lesser extent in the ARC. Triple labeling showed that a portion of the nesfatin-1 neurons activated in response to LPS within the NTS are catecholaminergic since they co-express tyrosine hydroxylase (TH). Our data therefore indicate that a portion of nesfatin-1 neurons of both the hypothalamus and brainstem are sensitive to peripheral inflammatory signals, and provide the first clues suggesting that centrally released nesfatin-1 may contribute to the neural mechanisms leading to endotoxaemic anorexia.


Asunto(s)
Inflamación/fisiopatología , Lipopolisacáridos , Proteínas del Tejido Nervioso/metabolismo , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Animales , Anorexia/inducido químicamente , Encéfalo/anatomía & histología , Encéfalo/metabolismo , Proteínas de Unión al Calcio , Proteínas de Unión al ADN , Lipopolisacáridos/inmunología , Lipopolisacáridos/farmacología , Masculino , Proteínas del Tejido Nervioso/genética , Neuronas/citología , Nucleobindinas , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , Ratas , Ratas Wistar
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